For the common meaning of "anorexic", see
Anorexia nervosa. For anorectics approved by regulatory bodies as anti-obesity treatments, see
Anti-obesity medication.
An anorectic or anorexic is a drug which reduces
appetite, resulting in lower food consumption, leading to
weight loss.[1] These substances work by affecting the
central nervous system or certain
neurotransmitters to create a feeling of fullness or reduce the desire to eat. The understanding of anorexiant effects is crucial in the development of interventions for
weight management, eating disorders, and related health concerns. The anorexiant effect can be induced through diverse mechanisms, ranging from hormonal regulation to neural signaling.
Ghrelin,
leptin, and
peptide YY are among the hormones involved in appetite control. Additionally, neurotransmitters such as
serotonin and
dopamine in the central nervous system contribute significantly to the regulation of food intake.
By contrast, an appetite stimulant is referred to as
orexigenic.
The term is (from the
Greekἀν- (an-) = "without" and ὄρεξις (órexis) = "appetite"), and such drugs are also known as anorexigenic, anorexiant, or appetite suppressant.
History
Used on a short-term basis clinically to treat
obesity, some appetite suppressants are also available
over-the-counter. Several appetite suppressants are based on a mix of natural ingredients, mostly using green tea as its basis, in combination with other plant extracts such as
fucoxanthin, found naturally in seaweed.
Drugs of this class are frequently
stimulants of the
phenethylamine family, related to
amphetamine.[citation needed]
The German and Finnish[2] militaries issued amphetamines (
Pervitin) to soldiers commonly during the
Second World War.[3] Similarly, the
UK military was supplied with more than 72 million
Benzedrine tablets and the
US military with an approximately equal amount for situations, in which fatigue was not deemed to be an acceptable option.[4] Following the war, large amphetamine surpluses were redirected for use on the black[5] and the civilian market. Indeed, amphetamine itself was sold commercially as an appetite suppressant until it was outlawed in most parts of the world in the late 1950s because of safety issues. Many amphetamines produce side effects, including
addiction,
tachycardia and
hypertension,[6] making prolonged unsupervised use dangerous.
Public health concerns
Epidemics of fatal
pulmonary hypertension and
heart valve damage associated with pharmaceutical anorectic agents have led to the withdrawal of products from the market. This was the case with
aminorex in the 1960s, and again in the 1990s with
fenfluramine (see:Fen-phen).[7] Likewise, association of the related appetite suppressant
phenylpropanolamine with
hemorrhagic stroke led the
Food and Drug Administration (FDA) to request its withdrawal from the market in the United States in 2000, and similar concerns regarding
ephedrine resulted in an FDA ban on its inclusion in dietary supplements in 2004. A Federal judge later overturned this ban in 2005 during a challenge by supplement maker Nutraceuticals. It is also debatable as to whether the ephedrine ban had more to do with its use as a
precursor in
methamphetamine manufacture rather than health concerns with the ingredient as such.[citation needed]
Non-pharmacological alternatives
Weight loss effects of water have been subject to some scientific research as a potential
non-pharmacological approach.[8] Drinking water prior to each meal may help in appetite suppression. Consumption of 500 mL (approximately 17 fl oz) of water 30 minutes before meals has been correlated with modest weight loss (1–2 kg; 2 to 4 lb) in obese men and women over a period of 8 to 12 weeks.[9][10]
Refeeding syndrome (RFS) is a
metabolic disturbance which occurs as a result of reinstitution of nutrition in people and animals who are
starved, severely
malnourished, or metabolically stressed because of severe illness. When too much food or liquid nutrition supplement is eaten during the initial four to seven days following a
malnutrition event, the production of
glycogen,
fat and
protein in cells may cause low
serum concentrations of
potassium,
magnesium and
phosphate.[11][12] The
electrolyte imbalance may cause neurologic, pulmonary, cardiac, neuromuscular, and hematologic symptoms—many of which, if severe enough, may result in death.
Refeeding syndrome can occur when someone does not eat for several days at a time usually beginning after 4–5 days with no food.[13]
Individuals with
drug abuse who begin to reintroduce normal eating habits after a period of malnutrition may be at increased risk for refeeding syndrome.[14]
List of anorectics
Numerous pharmaceutical compounds are marketed as appetite suppressants.
Fenfluramine† (one of the two components [the other being phentermine] of Fen-phen. Since discontinued to its potential for causing valvulopathies and
pulmonary hypertension)
Lorcaserin (withdrawn in the United States by the FDA due to an increased risk of cancer)[16]
^Lemke, Thomas L.; Williams, David A., eds. (2012). "Anorexiants as Pharmacologic Agents in the Management of Obesity". Foye's Medicinal Chemistry. Lippincott Williams & Wilkins. pp. 1451–6.
ISBN978-1-60913-345-0.
^Wood, Douglas M; Emmett-Oglesby, Michael W (1988). "Substitution and cross-tolerance profiles of anorectic drugs in rats trained to detect the discriminative stimulus properties of cocaine". Psychopharmacology. 95 (3): 364–8.
doi:
10.1007/BF00181948.
PMID3137623.
S2CID1105026.